U.S. Pat. Nos. 2,746,730 and 2,924,952 to Swenson et al. show prior art frozen or semi-frozen confection freezing chambers having conventional rubber cup seals between the mixing rotor shaft and a wall having an opening through which the shaft extends. Such seals do not accommodate any tendency of the shaft to nutate when the shaft bearing becomes worn and leakage tends to develop between the seal and the shaft.